The methods of making colored glass include (1) an ion-exchange method wherein inorganic salts of silver or copper are applied onto a glass surface and calcined, so that the ultrafine particles of the inorganic salt of silver or copper are allowed to penetrate into the glass substrate, thereby causing a transparent colloidal color development, and (2) a method wherein gold ions are mixed with a metal alkoxide solution and applied onto a substrate, followed by thermal treatment to deposit fine particles of the gold. Besides, (3) there is also known a method wherein a metallic film is vacuum deposited on a glass substrate by use of sputtering techniques.
On the other hand, the methods of forming a UV absorbing film on a glass substrate include a method wherein metal oxides serving as a UV absorbing component, e.g. zinc oxide, titanium oxide, cerium oxide and the like, are formed on a glass substrate according to a sol-gel technique or a sputtering technique thereby forming a UV absorbing film on the substrate. For instance, Japanese Laid-open Patent Application No. 6-192598 sets out a method wherein an UV absorbing film which contains CeO.sub.2 :TiO.sub.2 :SiO.sub.2 at ratios by weight of 64:18:18 is formed on a glass substrate by a sol-gel technique.
The films formed on glass substrates according to the above-mentioned methods are those which are colored but have no capability of UV absorption, or those which have the capability of UV absorption but are not colored. In Japanese Laid-open Patent Application No. 6-192598. there is described a glass article covered with a colored film which comprises fine particles of silicon oxide, titanium oxide and gold, and has a preferred composition comprising, for example, 85.about.3 wt % of TiO.sub.2, 40.about.0 wt % of SiO.sub.2 and 5.about.60 wt % of Au. However, this colored film-covered glass article is not satisfactory with respect to the UV cutting-off or screening performance when the content of TiO.sub.2 is not great. If the content of TiO.sub.2 is increased, a high UV screening performance is obtained and the film assumes a blue to pink color. Nevertheless, it is not possible to arbitrarily control the color of transmitted light, a UV transmittance and a visible light transmittance.